Problem: $\left[\begin{array} {ccc} -7& 7& 6& 0\\ -9& 9& 0& -7\\ -1& 9& 7& 0\\ -8& 1& 7& -3 \end{array}\right]$ What are the dimensions of the matrix?
Answer: The first dimension is the number of rows in the matrix. There are $4$ rows. The second dimension is the number of columns in the matrix. There are $4$ columns. In conclusion, the dimensions of the matrix are $4\times 4$.